It’s hard to believe the fifth and final season of Fox’s sci-fi drama, “Fringe,” is almost over. While the show’s less-than-ideal ratings resulted in this last, 13-episode season, the series has remained a cult favorite. No doubt, fans will be sad to say goodbye to the characters they’ve come to know through a roller coaster ride of alternate universes and rewritten timelines. But unfortunately, there’s no way to rewrite the future of “Fringe,” as the show is set to end with a 2-hour finale on January 18.

Whether you are a longtime fan who wants to refresh on the show’s mythology and best moments, or a newbie who wants to just know the basics so you can watch the finale with your friends, here are 10 essential episodes to watch before the series ends.

“The Road Not Taken” (Season 1, episode 19)

In this episode, viewers learned the true extent of the damage done by Walter Bishop and William Bell’s experiments on children. This had a huge impact on Olivia Dunham as she struggled to deal with her new, unsettling visions and some old childhood friends who turn up.

“There’s More Than One of Everything” (Season 1, episode 20)

This season finale was a race against enemy David Robert Jones, who tried to open a portal to another reality. As Jones left destruction in his wake, Olivia figured out that all the Pattern events seem to radiate from a place that became all too familiar to fans over the next few seasons: Reiden Lake in upstate New York.

“Jacksonville” (Season 2, episode 15)

Universes began to collide with a devastating impact, making the team return to Walter’s old lab in Florida to search for answers. In this episode, viewers learned more about Olivia’s past, her potential and Walter’s experiments on children -- not to mention a shocking revelation about one of the characters that changed the team forever.

“Peter” (Season 2, episode 16)

Possibly the most important episode of “Fringe” to watch, fans finally got some long awaited answers about the main characters’ motivations. Walter’s past relationship with the alternate universe was explained and the reasons why he might be responsible for what’s been happening in the world were revealed.

“Over There” (Season 2, 2-parter)

Peter crossed over to the other universe, so Olivia and Walter traveled there to get him back. This episode is exciting because not only do fans learn more about the characters’ doubles on the other side, but Leonard Nimoy’s William Bell makes another appearance. Oh, and Olivia and Peter share a touching moment viewers had all been waiting for!

“Entrada” (Season 3, episode 8)

The team learned that the Olivia they’ve been working with, and Peter got closer to, is not their Olivia! The race was on to find Faux-livia and figure out how to get their Olivia back. Meanwhile on the other side, Original-Olivia struggled to get free and discover that not everyone on the other side is as bad as they seemed.

“The End of All Things” (Season 4, episode 14)

This season was set in a timeline that never had a Peter, and everyone was still trying to get used to his sudden appearance. Despite this confusion, the old team was working together to find Olivia, who has been taken by David Robert Jones. Since Peter never existed in this timeline before, Jones was never killed so he's back causing trouble for the world.

“A Short Story About Love” (Season 4, episode 15)

Peter stayed away from Olivia to search for a way to return to his own timeline. He was convinced that she wasn't his Olivia and was scared of making the same mistake he made in season three. He ended up helping the Observer September return to their universe, which was hidden from him by the other Observers, and learned from September that he was, in fact, in his original timeline already.

“Letters of Transit” (Season 4, episode 19)

This is a must-see episode to understand the events of season five. Jumping forward to the year 2036, the Observers have conquered the world and the original Fringe team failed to stop them. Not all hope is lost however, as two FBI agents tried to find the original team, who had trapped themselves in amber, and release them to help the growing resistance fight against Observer control.

“Brave New World” (Season 4, 2-parter)

In this timeline, William Bell is behind the actions of David Robert Jones, and he wanted to collapse both universes in order to create one under his control. The power source for all of his plans turned out to be a member of the team, forcing one of them to make the ultimate sacrifice to save the world. This episode wrapped up events in this new timeline and had the team finally come together again as a family, and it also set up the events of season five.